Abstract The overall goal of this Program Project Group is to understand the mechanisms underlying renal fluid, electrolyte and macromolecule transport. Kinase and phosphatases are essential regulators of this process and thus, by extension, their target phosphorylation sites are important for mechanistic insight. This core will add value to the project group by bringing new capabilities and expertise in the identification and characterization of phosphorylation sites in proteins and proteomes. Dr. Jesse Rinehart will assume the role as the Phosphoproteomics Core Director and will bring expertise in phosphorylation mapping, quantitative proteomics, and phosphoprotein synthesis to the Program Project Group. Dr. Rinehart recently developed a new technology which enables site-specific incorporation of phosphoserine into proteins. This technology enables the synthesis of physiologically relevant phosphoproteins in an E. coli strain with an expanded genetic code. This unique technology and a recently published next- generation phosphoserine technology will be uniquely available to this Program Project Group. The combinations of established phosphoproteomics technologies and novel phosphoprotein synthesis technologies will enable a unique approach to validation and further exploration of the mechanisms of protein phosphorylation. The core will be an excellent learning environment and bring trainees from the Program Project Groups in close contact with proteomics experts in the Rinehart lab. This training environment will provide access to state-of-the-art technology to the individual members of the Project Group. Dr. Rinehart's research interests are closely aligned with the aims of this project group and, in addition to the technology, the unique lab environment is value added to the Program Project Group.